Ruth's credit card has an APR of 10.91%, and it computes finance charges using the previous balance method on a 30-day billing cycle. During the April billing cycle, she made a $45.17 payment on April 10th and a $88.34 purchase on April 17th. Her total at the start of May was $847.64. What was her balance at the beginning of April

Balance at the beginning of April = $796.83

Step-by-step explanation:

Let the balance at the beginning of April be "X"

The monthly interest rate = 0.1091/12

(X-45.17+88.34) * (1+0.1091/12) = 847.64 (Since she pays 45.17 and then takes on additional credit of 88.34)

(X+43.17) * 1.009091667 = 847.64

X+43.17 = 847.64/1.009091667 = 840

X = 840-43.17

X = 796.83

Balance at the beginning of April = $796.83